manpower requirements of economic development, as well as the social, or popular, demand for education. The two most important constraints on attaining these goals are the financial sacrifices the country is willing to make to reach them and, in many cases, the shortage of adequately trained teachers, a shortage that takes time to remedy, particularly when an attempt is made to diversify the system by strengthening areas such as technical education. Demographic trends in the less developed countries, which are forcing educational planners to aim at a moving target, are an integral part of the problem. In a country with a youth population of 1,000,000 increasing at 3 percent per annum, a rise in the enrollment rate from 50 percent to 75 percent in 10 years means an increase in enrollments, not of 250,000 but of 538,000. This example illustrates only one of the more obvious ways in which demographic trends are of vital importance to educational planning. To explain further the demographic constraints on educational advance, a quick summary of prospective demographic trends is in order. Population Structure As Table 5 shows, the less developed areas are sharply divided from the developed ones in terms of fertility, with birth rates more than twice as high as those in the developed regions. Mortality conditions vary more widely among the less developed countries, with crude death rates ranging from 9.5 per 1,000 in "Other East Asia" to 20.9 per 1,000 in Africa. If smaller regions TABLE 5 Crude Births and Death Rates by Major World Regions 1965-1970 Implied in United Nations Medium Variant Projections Crude Birth Rate Crude Death Rate Rate of Natural Increase World Total 32.9 14.4 18.5 More developed countries 18.5 8.5 10.0 Less developed countries 39.4 17.3 22.1 Mainland China 32.3 19.0 13.2 Other east Asiaa 37.5 9.5 28.0 South Asia 42.1 17.0 25.1 Africa 45.4 20.9 24.4 Latin America 39.0 9.9 29.1 Europe 16.6 9.9 6.7 U.S.S.R. 19.4 7.1 12.3 Northern America 21.3 9.4 11.9 Japan 15.6 7.7 7.9 aExcludes Japan. Source: (21, pp. 34-36).rcent by 1985.